Lubrication system for bearings

ABSTRACT

A forced lubricated bearing system is disclosed in which means are provided to recirculate lubricant leakage back to the bearing. In the illustrated embodiments, a water lubricated rubber bearing journals the shaft of a marine propulsion system or a pump. Water is pumped into the bearing for lubrication. A restricter limits the leakage rate from at leaat one end of the bearing. The leakage is collected and returned by an aspirator type pump in the lubricant supply line to the bearing. An inflatable seal operates to prevent leakage when the shaft is stationary and lubricant is not supplied to the bearing. In some instances, the inflatable seal is partially inflated to restrict the rate of leakage when the shaft is moving.

United States Patent Satterthwaite 1 July 31, 1973 LUBRICATION SYSTEMFOR BEARINGS Primary ExaminerCharles J Myhre Assistant Examiner-BarryGrossman [75 Inventor: James (,lenn Satterthwatte,

Portsmouth Va Attorney McNenny, Farrmgton, Pearne & Gordon I 73 IAssignee: The Johnson Rubber Company, [57] ABSTRACT Mlddlefield Ohm Aforced lubricated bearing system is disclosed in [22] Filed: Sept. 2,1971 which means are provided to recirculate lubricant leak- Appl. No.:177,334

age back to the bearing. In the illustrated embodiments, a waterlubricated rubber bearing journals the shaft of a marine propulsionsystem or a pump. Water is pumped into the bearing for lubrication. Arestricter limits the leakage rate from at least one end of the bearing.The leakage is collected and returned by an aspirator type pump in thelubricant supply line to the bearing. An inflatable seal operates toprevent leakage when the shaft is stationary and lubricant is notsupplied to the bearing. in some instances, the inflatable seal ispartially inflated to restrict the rate of leakage when the shaft ismoving.

12 Claims, 8 Drawing Figures PATENTEB JUL3 1 I975 3 749 4 4 SHEET 1 OF 3y 4 INVENTOR.

This invention relates generally to bearing lubrication systems and moreparticularly to a novel and improved force lubrication system for waterlubricated bearings or the like in which means are provided torecirculate lubricant leakage.

Water lubricated bearings are often used to support rotating shafts forpump and marine propulsion systems or the like. In many such systems,glands or seals are provided to limit leakage of the lubricant from atleast one end of the bearing. However, such glands or seals must usuallybe adjusted to permit some leakage so that they are themselveslubricated and cooled sufficiently to prevent rapid wear. In manyinstances, such leakage presents severe problems. For example, in marineinstallations the leakage normally accumulates in the bilge where itmixes with other leakage and waste. Because of such leakage, the bilgesmust be pumped with greater frequency. This is particularly undesirablesince the pumping of bilges contributes to the polution problem thatexists in many waterways. In other instances, for example in mines orthe like, the disposal of accumulated leakage presents severe problems.

PRIOR ART In the pending application, Ser. No. 8,278, filed Feb. 3,1970, an inflatable seal is disclosed which is inflated to provide apositive seal with the propeller shaft of a vessel when the vessel isnot under way and the shaft is not turning. Such seal reduces the amountof leakage accumulation but does not prevent all the leakage since it isnot fully inflated to positively prevent leakage when the vessel isunder way.

SUMMARY OF THE INVENTION In accordance with the preferred form of thepresent invention, a water lubricated bearing system is provided whichincludes means to automatically collect the leakage oflubricant and torecirculate such leakage back through the bearing. In such system, noneof the leakage accumulates. When the system is employed in a marinevessel, the leakage does not reach the bilge and, therefore, does notcontribute to the accumulation of waste in the bilge. When the system isused in a nonmarine installation, it eliminates the need to dispose ofthe leakage.

In accordance with one important aspect of this invention, the leakageis automatically pumped back into the lubricant supply and is returnedto the bearing. In the illustrated embodiment, the lubricant underpressure, as it flows to the bearing, passes through a jet or aspiratortype pump to draw the leakage back into the lubricant supply systemwhich carries the lubricant to the bearing. Therefore, it is notnecessary to provide separate power means and separate pumping means torecirculate the leakage. Also, the suction of the main lubricant pumpcannot be adversely affected by temporary evacuation of the seal leakagerecirculation line which is located on the discharge side of the mainlubricant pump.

In accordance with another aspect of this invention, an inflatable sealis utilized during the operation of the system to limit the rate ofleakage from one end of the bearing to the desired rate. However, whenthe equipment is not operating and the shaft is stationary, such seal isfurther inflated to positively seal and prevent all leakage. Thus, asingle seal performs the dual functions of controlling leakage underoperating conditions and entirely preventing leakage under nonoperatingconditions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation partiallyin section of a pump, the rotor of which is joumaled in a waterlubricated rubber bearing and which is provided with a forcedlubrication system in accordance with this invention;

FIG. 2 is an enlarged fragmentary section of the pump of FIG. 1illustrating the inflatable flow restricter and seal, and alsoillustrating the leakage collector system;

FIG. 3 is an end view taken generally at 33 of FIG. 1 with the collectorring partially broken away for purposes of illustration;

FIG. 4 is an enlarged fragmentary section of the aspirator for pumpingthe leakage back into the bearing;

FIG. 5 is a fragmentary longitudinal section of a modified bearingsystem in which a leakage restricter is provided at both ends of a pumpbearing;

FIG. 6 is a fragmentary schematic illustration of a ships propulsionsystem incorporating this invention;

FIG. 7 is an enlarged fragmentary longitudinal section of the gland areaof the propulsion system illustrated in FIG. 6; and

FIG. 8 is an enlarged fragmentary section of an embodiment of a shipspropulsion system similar to FIG. 6 in which the gland is replaced by aninflatable restricter and seal.

DETAILED DESCRIPTION OF THE DRAWING FIGS. 1 through 4 illustrate a pumpsystem incorporating this invention. Theillustrated pump is of the typeoften used in hydraulic dredges, slurry pump operations and the like.Such pump is provided with a housing assembly 10 consisting ofa bearingsupport housing section 11, a main pump housing section 12, and an inlethousing'section 13. An inlet ring 14 is carried by the inlet housingsection 13.

A rotor or impeller assembly 16 includes an impeller 17, a drive shaft18, and a bearing sleeve 19. In the illustrated embodiment, the bearingsleeve 19 includes an inner tubular section 21, drivingly connected to aflange 20 on the end of the drive shaft 18, and a relatively largecylindrical journal hub or bearing section 22 joined to the innertubular section 21 by an end wall 23 and supports 23a. The end wall 23is secured tightly against the adjacent surface of the impeller 17 bystud bolts 25.

Mounted in the bearing support housing section are a plurality of rubberstaves 27 which cooperate to encircle the outer tubular bearing section22 and provide a water lubricated rubber bearing in which the impellerassembly 16 is jounaled. Preferably, the staves 27 are subjected toendwise releasable compressive stress to secure them in position in themanner disclosed in the pending application, Ser. No. 653,796, filedJuly 17, I967. The staves are compressed axially between a head liner 28mounted in the housing assembly 10 and a lantern ring 29. The lanternring 29 is secured in position by an end housing 31 secured to the endof the housing section 11 by bolts (not illustrated).

An inflatable ring 32 formed of elasto'meric material is secured in theend housing 31 by a collector ring 33 secured to the end housing bybolts (not illustrated). The ring 32 provides a flexible wall 34 and anair chamber 36 which is pressurized to move the wall toward the outerbearing surface of the bearing section 2.2. Reference should be made tothe pending application, Ser. No. 8,278, filed Feb. 3, I970 for adetailed description of the structure and operation of such aninflatable ring. A valved stem assembly 37 communicates with the chamber36 to permit it to be pressurized or exhausted as required.

Lubricating water-is supplied to the bearing under pressure bya waterpump 38 schematically illustrated in FIG. 1 through a supply line 39connected to an inlet port 41 formed in the housing section 11 adjacentto the lantern ring 29. The lantern ring is formed with an externaldistribution groove 42 which communicates through a plurality of radialports 43 symmetrically located around the ring to the interior of thering. This insures that the supply of water lubricant is evenlydistributed around the bearing.

When the lubricating water is supplied to the bearing, the majority ofthe -water flows along lubricating grooves 44 formed in the staves 27 tolubricate the bearing. The majority of the lubricant is exhausted ordischarged from the hearing at the impeller end thereof and flows outthrough the space 46 between the housing and the impeller 17 where it isdischarged with the main pump discharge through a discharge opening inthe pump (not illustrated). Some of the lubricant, however, flows in theopposite direction along the bearing section 22 past the inflatable ring32 as lubricant leakage. The ring 32 is inflated to an extent which willpermit a controlled amount of leakage therepast when the pump isoperating. It is necessary to provide a limited amount of leakage sothat the inner wall 34 is adequately lubricated to insure minimum wearand drag losses on the journal surface.

The flow of such leakage continues along the housing and the bearingsection 22 until it reaches a collector groove 47 formed in thecollector ring 33. The radial wall 48, which faces in a directionaxially away from the bearing surface and which is located within thering 33, serves as a stop for such flow. The centrifugal force on aleakage oflubricant flowing along the bearing section 22 causes suchleakage to be thrown outwardly into the collector groove 47 and preventsit from flowing radially inward along the end wall 48. The lubricantleakage flows down along the collector groove and is collected at thebottom thereof at 49.

A return line 51 is connected between the bottom of the collector grooveand an aspirator pump 52 to return the collected leakage to the supplyline 39. Referring to FIG. 4, the aspirator pump includes an aspiratorhousing 53 cooperating with the upstream portion 54 of the supply line39 to define an annular chamber 56 to open to the inlet end of thedownstream portion 57 of the supply line 39. The return line 51 connectsto the chamber 56. When water is flowing through the aspirator, a vacuumis developed in the chamber 56 and the jet of lubricant passing throughthe aspirator pumps the leakage back into the downstream portion 57 ofthe supply line and returns it to the bearing. It should be understoodthat other types of jet pumps or the like, such as Venturi type pumps,may be used to pump the leakage lubricant back into the supply line. Inthe illustrated pump, the upstream portion 54 of the supply line 39 isshaped to provide a nozzel which produces a jet directed into thedownstream portion 57. In any event, the aspirator pump is capable ofproducing a sufficient suction head to pump the accumulated lubricantleakage through the return line 51 back into the supply line 39 at alltimes during operations.

If the pump 12 is utilized in a system wherein a positive pressureexists in the pump chamber when the pump is not operating, theinflatable ring 32 is pressurized at such time a sufficient amount toprovide a positive seal with the bearing journal section 22 topositively prevent leakage of water out of the bearing, since the flowof lubricant would not normally be provided during such periods, and theaspirator 52 would then not be able to pump away the accumulatedleakage. in such a system, a check valve is provided in the supply line39 between the bearing and the aspirator 52 to prevent reverse flow. Insuch a system, the ring is deflated prior to the commencement ofoperation of the pump a sufficient amount to again allow a controlledleakage of lubricant past the ring to prevent damaging wear to the ring.

In the past, glands having packing rings, radially loaded lip seals orthe like have generally been provided to minimize or control the leakagefrom the bearing. Such packing rings, even through they are nor mallyadjusted to allow a limited amount of leakage, provide a substantialfriction and, consequently, consume power. With the illustratedstructure in which a rubber ring is controllably inflated to permit adesirable rate of leakage so that sufficient lubrication of the sealsurface is provided and a very low friction is encountered and much lesspower is wasted. Consequently in a pump in accordance with theillustrated embodiment, a greater percentage of the power supplied tothe pump is utilized to actually pump material, and far less power islost in friction. Consequently, efficiency is improved substantiallywhile seal leakage by conventional standards is entirely eliminated.

FIG. 5 illustrates a pump bearing system similar to FIGS. 1 through 4.However, in this embodiment flow restricters are provided at both endsof the bearing. Similar reference numerals will be used to designatesimilar parts with a prime added to indicate references beingmade to theembodiment of FIG. 5. Here again, the impeller 17 is supported by abearing sleeve 19' within water lubricated rubber bearing staves 27which encircle the outer journal hub or bearing section 22'. Waterlubricant is supplied to the bearing through a supply line 39' and alantern ring 29 in the same manner as the first embodiment. Also, aninflatable ring 32' is mounted at the outer end of the bearing tocontrol the leakage from that end of the bearing. Leakage past the ring32' is again collected within a collector ring 33 and returned to thesupply line 39' by an aspirator pump in the same manner as in the firstembodiment of FIGS. Ithrough 4.

In this embodiment, however; a second inflatable ring 40' is mountedwithin the headliner 28' at the end of the bearing adjacent to theimpeller 17'. The inflatable ring 40' has the same structure as theinflatable ring 32' and can be pressurized in the same manner to controlthe rate of flow from the bearing into the main pump. The principalfunction of the inflatable ring 40' is to provide means for adjustingthe rate of flow of lubricant through the bearing. In some instances,flow rates of lubricant are greater than the rates required for goodlubrication if means are not provided to restrict the flow into the mainpump. The pressure of the inflatable ring in this embodiment is adjustedto produce a flow rate which is sufficient to provide proper lubricationofthe bearing and to cause proper operation of the aspirator pumpwithout excessive flow. This eliminates the excessive power consumptionof the lubricant supply pump required by excessive flow.

ln instances where a positive pressure exists in the main pump housing12, when the main pump is not operating, the inflatable ring 40 may befully inflated to prevent any flow of lubricant into the bearing.Because the inflatable ring 40 is upstreamed from the lubricant supplyline 39' at such time, full inflation of the inflatable ring 40eliminates the requirement for a check valve in a line 39'.

FIGS. 6 and 7 illustrate an embodiment of this invention applied to thepropulsion system ofa ship in which the hull of the ship isschematically illustrated at 61. A propeller drive shaft 62 extendsthrough a stern bearing tube 63 and outboard strut 64 to support androtate a propeller 66. Water lubricated rubber bearings are provided inthe stern tube 63 and the outboard strut 64 to journal the shaft forrotation about its central axis. At the inner end of the stern tube 63,a stuffing box assembly 67 is provided through which a water lubricantis pumped to the rubber bearing within the stern tube 63 by a pump 68.

Referring to FIG. 7, the stufflng box 67 is provided with an inflatablering seal 69 substantially adjacent to the rearward end of the bearingstave 71 of the rubber bearing. Reference may be made to the copendingapplication, Ser. No. 791,082, filed Jan. 14, 1969, for a more detaileddescription of the structure and operation of such stuffing boxes, andto the pending application, Ser. No. 653,796, filed July 17, 1967, for adetailed description of a preferred stave bearing system.

The lubricant supply is pumped from the pump 68 through a supply line 72between the seal 69 and a packing gland 73. The packing gland 73 isadjustably compressed by a gland ring 74 which is positioned by bolttype fasteners 76. The inboard end of the gland ring 74 is formed with acollector ring 77 which provides an annular groove 78 in which theleakage of lubricant is collected. A slinger ring 79 is clamped by aclamp ring 81 to the shaft 62 to provide a radial wall within thecollector groove 78. A return line 83 connects the bottom of thecollector groove 78 to an aspirator 84 in the lubricant supply line 72.The structure of the aspirator may be the same as the aspirator 52 ofthe embodiment of FIGS. 1 through 4.

In normal operation while the shaft 62 is rotating, lubricating water ispumped through the supply line 72 and flows past the deflected ring seal69 to the bearing staves 71. Such water is discharged through therearward end of the bearing into the surrounding water. The packinggland 73 is adjusted so that a limited amount of leakage flows along theshaft 62. past the gland to the slinger 79. Such leakage provideslubrication and cooling for the gland. When the leakage reaches theslinger, it is thrown by centrifugal force and gravity outward into thecollector groove 78 and is collected at the bottom thereof. Theaspirator 84 pumps such leakage back through the return line 83 to thelubricant supply line 72 and back to the bearing. Consequently, noleakage of bearing lubricant reaches the ships bilge.

In this embodiment the seal 69 is inflated when the ship is not underway and the shaft is not rotating. When inflated, the seal 69 provides apositive seal to prevent leakage of external water in through thebearing and gland, thus preventing accumulation of water in the bilgewhen the ship is not under way and when the pump 68 is not functioningto supply lubricant to the bearing. Prior to starting the shaft, theseal 69 is deflated and the pump 68 is operated to supply lubricant tothe bearing. Since leakage is prevented, both when the ship is under wayand when the ship is notunder way, there is no accumulation of lubricantleakage water in the ships bilge.

FIG. 8 illustrates a second embodiment of a ship's propulsion system inwhich an inflatable seal is used both to control the rate of leakagewhile the ship is under way, and to prevent leakage when the ship is notunder way. In this embodiment a lantern ring 86 is provided at theinboard end of the staves 87 through which lubricant is pumped from thelubricant supply 88. In this embodiment, however, a packing gland is notutilized to control the leakage while the ship is under way. Instead, aninflatable ring 89 is provided inboard of the lantern ring 86 to controlthe rate of leakage inboard along the shaft 91 while the ship is underway. Here again, a slinger 92 is located within the collector groove 93ofa collector ring 94, and a return line and aspirator similar to thereturn line 83 and aspirator 84 illustrated in FIG. 7 are utilized topump the leakage from the collector groove 93 back into the supply line88.

When the ship is under way, the pressure in the inflatable ring 89 isadjusted to provide the desired rate of leakage along the shaft 91. Therate must be sufficient to provide lubrication for the ring to preventits wear, but must be sufficiently slow so that the aspirator system hascapacity to pump the leakage back into the bearing. Here again, Venturitype jet pumps may be utilized instead of an aspirator if desired. Whenthe ship is not under way, the ring seal 89 is further inflated topositively prevent leakage along the shaft 91 into the bilge. A checkvalve 96 is provided in the line 88 to prevent reverse flow while thepump is not supplying lubricant under pressure. Such check valve is notrequired in the embodiment of FIGS. 6 and 7 since the seal 69, wheninflated, prevents the water from reaching the supply line 72. A secondinflatable seal ring may also be used on the sternward side of thelantern ring 86 instead of a check valve to provide a positiveseal.

In all of the embodiments of this invention, means are provided toprevent the accumulation of lubricant leakage and to recirculate suchleakage back through the bearing. Consequently, the problem of leakageaccumulation is eliminated without requiring separately driven pumpmeans to dispose of the accumulated leakage. Further, in the preferredforms of this invention, an inflatable ring is provided to control therate of leakage while the system is operating and to positively preventall leakage when the system is not operating. Such inflatable ring, inmost instances, is used to replace the packing gland utilized in priorsystems, thus eliminating the power loss and wear occurring in suchglands.

Although preferred embodiments of this invention are illustrated, it isto be understood that various modifications and rearrangement of partsmay be resorted to without departing from the scope of the inventiondisclosed and claimed herein.

What is claimed is:

l. A forced lubricated bearing system comprising a bearing, a shaftjournaled in said bearing, lubricant supply means operable to supplylubricant to said bearing under pressure for flow therethrough,restricter means located at least at one end of said bearing operable topermit restricted leakage of said lubricant from one end of saidbearing, collector means operable to collect said leakage oflubricant,and pump means operating in response to flow of lubricant from saidsupply means to said bearing to automatically pump said leakage of saidlubricant back into said bearing.

2. A forced lubricated bearing system as set forth in claim I whereinsaid bearing is a water lubricated bearmg.

3. A forced lubricated bearing system as set forth in claim 2 whereinsaid pump means is an aspirator pump connected between said lubricantsupply means and said bearing.

4. A forced lubricated bearing system as set forth in claim 3 whereinsaid collector means includes an annular collector groove around saidshaft, and a radially extending surface on said shaft within saidcollector groove facing in a direction axially away from said bearing.

5. A forced lubricated bearing system as set forth in claim 4 whereinsaid restricter means includes a seal operable to prevent said leakageof lubricant when said shaft is stationary.

6. A forced lubricated bearing system as set forth in claim 5 whereinsaid seal is inflatable to prevent leakage when said shaft is stationaryand deflatable to permit flow of lubricant therepast when said shaft ismovmg.

7. A forced lubricated bearing system as set forth in claim 5 whereinsaid seal is inflatable to prevent leakage when said shaft is stationaryand partially inflated to permit said restricted leakage of saidlubricant from said one end of said bearing when said shaft is moving.

8. A forced lubricated bearing system as set forth in claim 7 whereinsaid bearing is a water lubricated elastomeric bearing and said seal isformed of elastomeric material.

9. A bearing system comprising a bearing, a shaft journaled in saidbearing, lubricant between said bearing and said shaft, restricter meanslocated at least at one end of said bearing operable to permitrestricted leakage of said lubicant from said one end of said bearing,collector means operable to collect said leakage of lubricant, saidrestricter means including a seal fully inflatable to prevent saidleakage of lubricant when said shaft is stationary and partiallyinflatable to permit said restricted leakage when said shaft is moving,and means to pump said leakage of lubricant from said collector meansback into said bearing.

10. A bearing system as set forth in claim 9 wherein pressure means areprovided to supply said lubricant to said bearing for flow therethrough,and said pump means operates in response to said flow of lubricant tosaid bearing.

ll. A bearing system as set forth in claim 10 wherein said collectormeans includes an annular groove around said shaft and a generallyradially extending surface on said shaft within said groove facing in adirection away from said bearing.

12. A forced lubricated bearing system comprising a bearing, a shaftjournaled in said bearing, lubricant supply means operable to supplylubricant to said bearing under pressure for flow therethrough,restricter means located at least at one end of said bearing operable topermit restricted leakage of said lubricant from one end of saidbearing, collector means operable to collect said leakage of lubricant,pump means to automatically pump said leakage of said lubricant backinto said hearing, and check valve means preventing backflow oflubricant through said lubricant supply means.

1. A forced lubricated bearing system comprising a bearing, a shaftjournaled in said bearing, lubricant supply means operable to supplylubricant to said bearing under pressure for flow therethrough,restricter means located at least at one end of said bearing operable topermit restricted leakage of said lubricant from one end of saidbearing, collector means operable to collect said leakage of lubricant,and pump means operating in response to flow of lubricant from saidsupply means to said bearing to automatically pump said leakage of saidlubricant back into said bearing.
 2. A forced lubricated bearing systemas set forth in claim 1 wherein said bearing is a water lubricatedbearing.
 3. A forced lubricated bearing system as set forth in claim 2wherein said pump means is an aspirator pump connected between saidlubricant supply means and said bearing.
 4. A forced lubricated bearingsystem as set forth in claim 3 wherein said collector means includes anannular collector groove around said shaft, and a radially extendingsurface on said shaft within said collector groove facing in a directionaxially away from said bearing.
 5. A forced lubricated bearing system asset forth in claim 4 wherein said restricter means includes a sealoperable to prevent said leakage of lubricant when said shaft isstationary.
 6. A forced lubricated bearing system as set forth in claim5 wherein said seal is inflatable to prevent leakage when said shaft isstationary and deflatable to permit flow of lubricant therepast whensaid shaft is moving.
 7. A forced lubricated bearing system as set forthin claim 5 wherein said seal is inflatable to prevent leakage when saidshaft is stationary and partially inflated to permit said restrictedleakage of said lubricant from said one end of said bearing when saidshaft is moving.
 8. A forced lubricated bearing system as set forth inclAim 7 wherein said bearing is a water lubricated elastomeric bearingand said seal is formed of elastomeric material.
 9. A bearing systemcomprising a bearing, a shaft journaled in said bearing, lubricantbetween said bearing and said shaft, restricter means located at leastat one end of said bearing operable to permit restricted leakage of saidlubicant from said one end of said bearing, collector means operable tocollect said leakage of lubricant, said restricter means including aseal fully inflatable to prevent said leakage of lubricant when saidshaft is stationary and partially inflatable to permit said restrictedleakage when said shaft is moving, and means to pump said leakage oflubricant from said collector means back into said bearing.
 10. Abearing system as set forth in claim 9 wherein pressure means areprovided to supply said lubricant to said bearing for flow therethrough,and said pump means operates in response to said flow of lubricant tosaid bearing.
 11. A bearing system as set forth in claim 10 wherein saidcollector means includes an annular groove around said shaft and agenerally radially extending surface on said shaft within said groovefacing in a direction away from said bearing.
 12. A forced lubricatedbearing system comprising a bearing, a shaft journaled in said bearing,lubricant supply means operable to supply lubricant to said bearingunder pressure for flow therethrough, restricter means located at leastat one end of said bearing operable to permit restricted leakage of saidlubricant from one end of said bearing, collector means operable tocollect said leakage of lubricant, pump means to automatically pump saidleakage of said lubricant back into said bearing, and check valve meanspreventing backflow of lubricant through said lubricant supply means.